drm/amd/display: Add dsc pre-validation in atomic check

[Why]
The previous change:
"Add affected crtcs to atomic state for dsc mst unplug"
forces modeset on all added crctc regardless whether timing changed or not.
Per our implementation of dsc we need modeset only if timing changed.
Otherwise dsc can be programmed incorrectly leading to dsc engine hang.

[How]
During atomic_check pre-compute dsc params.
Only set mode_changed if timing is changed.

Reviewed-by: Hersen Wu <hersenwu@amd.com>
Acked-by: Jasdeep Dhillon <jdhillon@amd.com>
Signed-off-by: Roman Li <Roman.Li@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 196 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
index 9305630e9505..1feb06020666 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
@@ -47,6 +47,9 @@
 
 #if defined(CONFIG_DRM_AMD_DC_DCN)
 #include "dc/dcn20/dcn20_resource.h"
+bool is_timing_changed(struct dc_stream_state *cur_stream,
+		       struct dc_stream_state *new_stream);
+
 #endif
 
 static ssize_t dm_dp_aux_transfer(struct drm_dp_aux *aux,
@@ -1080,4 +1083,197 @@ bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
 	return true;
 }
 
+static bool
+	pre_compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
+					      struct dc_state *dc_state,
+					      struct dsc_mst_fairness_vars *vars)
+{
+	int i, j;
+	struct dc_stream_state *stream;
+	bool computed_streams[MAX_PIPES];
+	struct amdgpu_dm_connector *aconnector;
+	int link_vars_start_index = 0;
+
+	for (i = 0; i < dc_state->stream_count; i++)
+		computed_streams[i] = false;
+
+	for (i = 0; i < dc_state->stream_count; i++) {
+		stream = dc_state->streams[i];
+
+		if (stream->signal != SIGNAL_TYPE_DISPLAY_PORT_MST)
+			continue;
+
+		aconnector = (struct amdgpu_dm_connector *)stream->dm_stream_context;
+
+		if (!aconnector || !aconnector->dc_sink)
+			continue;
+
+		if (!aconnector->dc_sink->dsc_caps.dsc_dec_caps.is_dsc_supported)
+			continue;
+
+		if (computed_streams[i])
+			continue;
+
+		if (!is_dsc_need_re_compute(state, dc_state, stream->link))
+			continue;
+
+		mutex_lock(&aconnector->mst_mgr.lock);
+		if (!compute_mst_dsc_configs_for_link(state,
+						      dc_state,
+						      stream->link,
+						      vars,
+						      &link_vars_start_index)) {
+			mutex_unlock(&aconnector->mst_mgr.lock);
+			return false;
+		}
+		mutex_unlock(&aconnector->mst_mgr.lock);
+
+		for (j = 0; j < dc_state->stream_count; j++) {
+			if (dc_state->streams[j]->link == stream->link)
+				computed_streams[j] = true;
+		}
+	}
+
+	return true;
+}
+
+static int find_crtc_index_in_state_by_stream(struct drm_atomic_state *state,
+					      struct dc_stream_state *stream)
+{
+	int i;
+	struct drm_crtc *crtc;
+	struct drm_crtc_state *new_state, *old_state;
+
+	for_each_oldnew_crtc_in_state(state, crtc, old_state, new_state, i) {
+		struct dm_crtc_state *dm_state = to_dm_crtc_state(new_state);
+
+		if (dm_state->stream == stream)
+			return i;
+	}
+	return -1;
+}
+
+static bool is_link_to_dschub(struct dc_link *dc_link)
+{
+	union dpcd_dsc_basic_capabilities *dsc_caps =
+			&dc_link->dpcd_caps.dsc_caps.dsc_basic_caps;
+
+	/* only check phy used by dsc mst branch */
+	if (dc_link->type != dc_connection_mst_branch)
+		return false;
+
+	if (!(dsc_caps->fields.dsc_support.DSC_SUPPORT ||
+	      dsc_caps->fields.dsc_support.DSC_PASSTHROUGH_SUPPORT))
+		return false;
+	return true;
+}
+
+static bool is_dsc_precompute_needed(struct drm_atomic_state *state)
+{
+	int i;
+	struct drm_crtc *crtc;
+	struct drm_crtc_state *old_crtc_state, *new_crtc_state;
+	bool ret = false;
+
+	for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
+		struct dm_crtc_state *dm_crtc_state = to_dm_crtc_state(new_crtc_state);
+
+		if (!amdgpu_dm_find_first_crtc_matching_connector(state, crtc)) {
+			ret =  false;
+			break;
+		}
+		if (dm_crtc_state->stream && dm_crtc_state->stream->link)
+			if (is_link_to_dschub(dm_crtc_state->stream->link))
+				ret = true;
+	}
+	return ret;
+}
+
+void pre_validate_dsc(struct drm_atomic_state *state,
+		      struct dm_atomic_state **dm_state_ptr,
+		      struct dsc_mst_fairness_vars *vars)
+{
+	int i;
+	struct dm_atomic_state *dm_state;
+	struct dc_state *local_dc_state = NULL;
+
+	if (!is_dsc_precompute_needed(state)) {
+		DRM_DEBUG_DRIVER("DSC precompute is not needed.\n");
+		return;
+	}
+	if (dm_atomic_get_state(state, dm_state_ptr)) {
+		DRM_DEBUG_DRIVER("dm_atomic_get_state() failed\n");
+		return;
+	}
+	dm_state = *dm_state_ptr;
+
+	/*
+	 * create local vailable for dc_state. copy content of streams of dm_state->context
+	 * to local variable. make sure stream pointer of local variable not the same as stream
+	 * from dm_state->context.
+	 */
+
+	local_dc_state = kmemdup(dm_state->context, sizeof(struct dc_state), GFP_KERNEL);
+	if (!local_dc_state)
+		return;
+
+	for (i = 0; i < local_dc_state->stream_count; i++) {
+		struct dc_stream_state *stream = dm_state->context->streams[i];
+		int ind = find_crtc_index_in_state_by_stream(state, stream);
+
+		if (ind >= 0) {
+			struct amdgpu_dm_connector *aconnector;
+			struct drm_connector_state *drm_new_conn_state;
+			struct dm_connector_state *dm_new_conn_state;
+			struct dm_crtc_state *dm_old_crtc_state;
+
+			aconnector =
+				amdgpu_dm_find_first_crtc_matching_connector(state,
+									     state->crtcs[ind].ptr);
+			drm_new_conn_state =
+				drm_atomic_get_new_connector_state(state,
+								   &aconnector->base);
+			dm_new_conn_state = to_dm_connector_state(drm_new_conn_state);
+			dm_old_crtc_state = to_dm_crtc_state(state->crtcs[ind].old_state);
+
+			local_dc_state->streams[i] =
+				create_validate_stream_for_sink(aconnector,
+								&state->crtcs[ind].new_state->mode,
+								dm_new_conn_state,
+								dm_old_crtc_state->stream);
+		}
+	}
+
+	if (!pre_compute_mst_dsc_configs_for_state(state, local_dc_state, vars)) {
+		DRM_DEBUG_DRIVER("pre_compute_mst_dsc_configs_for_state() failed\n");
+		goto clean_exit;
+	}
+
+	/*
+	 * compare local_streams -> timing  with dm_state->context,
+	 * if the same set crtc_state->mode-change = 0;
+	 */
+	for (i = 0; i < local_dc_state->stream_count; i++) {
+		struct dc_stream_state *stream = dm_state->context->streams[i];
+
+		if (local_dc_state->streams[i] &&
+		    is_timing_changed(stream, local_dc_state->streams[i])) {
+			DRM_DEBUG_DRIVER("crtc[%d] needs mode_changed\n", i);
+		} else {
+			int ind = find_crtc_index_in_state_by_stream(state, stream);
+
+			if (ind >= 0)
+				state->crtcs[ind].new_state->mode_changed = 0;
+		}
+	}
+clean_exit:
+	for (i = 0; i < local_dc_state->stream_count; i++) {
+		struct dc_stream_state *stream = dm_state->context->streams[i];
+
+		if (local_dc_state->streams[i] != stream)
+			dc_stream_release(local_dc_state->streams[i]);
+	}
+
+	kfree(local_dc_state);
+}
 #endif